1. Field of the Invention
The present invention relates to an actuator powered apparatus that has application in assembly plants for clamping, welding and other assembly functions that are common in the manufacture and assembly of vehicles such as, for example, automobiles. More particularly, the invention is related to a dual action fluid powered apparatus that is equipped with two elongate arms that are spaced apart from one another. The elongate arms operate independently of one another. The elongate arms are positioned within a common housing that supports fluid drive cylinders that are attached to each elongate arm. In one embodiment, a rack gear and pinion gear arrangement is utilized to immobilize the elongate arms, thus, minimizing drift of the elongate arms because of an imbalance in forces applied to the elongate arms.
2. Description of the Prior Art
The prior art is replete with the utilization of single hydraulic and pneumatic cylinders in conjunction with mechanical devices. Many prior applications of fluid drive cylinders employ the telescoping variety when one cylinder acts within another cylinder to enhance a given force. Also, the prior art discloses a variety of devices that employ a rack and gear combination to change arcuate motion to a translatory function, or vice versa.
The present invention differs from the rack and pinion gear driven load grip device that is shown and described in U.S. Pat. No. 2,595,131, entitled "Load Grip Means for Trucks and the Like" issued Apr. 29, 1952, to Leslie G. Ehmann. FIG. 1 of the Ehmann patent depicts a pair of spaced apart cylinders 26 that are oriented parallel to one another. In cross-section, the cylinders are square in configuration and have a cylindrical bore located along the longitudinal axis of the cylinder. One of the four sides of each cylinder contains a rack gear. The rack gears of the cylinders mesh with the teeth of a pinion gear that is attached to a flange. Each one of the cylinders is powered by a piston that is connected to a piston rod. The piston and the piston rod are contained within the cylinder in the usual fashion, with only the end of the piston rod protruding from the cylinder. The ends of the piston rods are fixed, thus, when fluid pressure is applied to the piston head, the cylinder with its attached rack gear moves in a linear direction. The pinion gear is fixed against rotation by its attached flange. Consequently, when fluid pressure is applied to the piston heads, the rack gear containing cylinders walk around the teeth of the fixed pinion gear. In this manner, a torque is developed to rotate the entire plate to which the cylinders and their accompanying pistons are attached.
The present invention differs from the above described device in that the power generating fluid driven cylinders are separate from the rods or elongate arms that contain the rack gear teeth. Thus, any malfunction of the piston head, or its seals, does not affect the block assembly that houses the elongate arms. Then, too, the present invention provides elongate arms that can move independently of one another. In the previously discussed prior art device, the two arms are coupled together in a positive manner through the common pinion gear.
In U.S. Pat. No. 2,605,751, entitled "Fluid Pressure Tool Slide Control Assembly" issued Aug. 5, 1952, to Richard D. Perry et al, there is shown an apparatus for controlling the feed of a machine cutting tool. FIG. 3 of Perry et al shows a housing 11 that contains two piston chambers 19 and 20 that are in tandem. Each piston chamber 19 and 20 contains a piston head that is connected to a common piston rod 65. The smaller piston 63 is driven hydraulically with the fluid medium being oil. The oil can be metered very slowly to either side of the piston 19, providing for very slow axial movement of the piston rod. The larger piston 20 is driven pneumatically with the fluid medium being air. A cutting tool is responsive to the axial movement of the piston rod 65. The cutting tool can be moved into and out of engagement with a workpiece by utilizing air pressure on one side or the other of the piston 20. Incremental movement of the cutting tool is then achieved by metering oil to one side or the other of the piston 19. Thus, the tool is fed rapidly by the pneumatic cylinder from its rest position substantially into engagement with the workpiece and is then fed slowly at a rate determined by the setting of a throttling valve which forms a part of the hydraulic speed control.
The present invention differs from the above described cutting control for a tool in that two movable tool carrying elongate arms are in separate chambers, not in tandem as in the Perry et al reference. In one embodiment of the present invention, very precise control of the tool is achieved by means of a rack and gear arrangement.